by
Hall, Prentice

Answer

y=3

Work Step by Step

This question involves mental math. There is a negative in front of the y, so doing it the traditional way is a bit difficult to do in our head. Thus, we ask ourselves 7 minus what number equals 4. We know that 4+3 is 7, so thus we remember that 7 minus 3 is 4, meaning that y=3.